New calibration kit for 750 Street Demon carburetors

On April 24, the Street Demon production line issued its first 750 Street Demon carburetors. In a week’s time the assembly cells will be expanded, allowing production volumes to double. In the meantime details of a calibration kit for the new carburetor have emerged.

Via an assortment of metering rods, primary and secondary jets, and piston springs, fuel flow rates can be adjusted above and below the production calibrations. Thus the carburetor performs richer or leaner—you can calibrate it to the exact air-fuel ratios for any specific engine or condition.

In appearance the new, bigger 750 (right) looks identical to its forerunner, except for the size of its primary throttle valves, which have been enlarged in diameter from 1-3/16th to 1-11/16th. The main venturii diameter has also been enlarged. Predictably the calibrations have also been increased.

Commonly fuel flow alterations are initiated by changes in altitude, camshaft, higher compression ratios, or engine displacement—and sometimes by unequal distribution from an intake manifold at different engine speeds.

Generally, metering rods are changed to adjust air-fuel ratios in finer increments while jets are changed to affect larger increments. In summary, the tuning kit is useful for correcting hesitation troubles or eye-watering exhaust fumes or puffs of smoke under acceleration. At the chassis dynamometer it quickly enables the tuner to accomplish maximum efficiency.

All components in the Demon calibration kit are supplied in pairs and all jets and needles are stamped for easy identification. Now available under part number 1931, the new 750 Street Demon calibration kit is priced at $57.69.